How to Fix a Leaking Toilet (2024)

Everything should be as reliable as a toilet. It’s not unusual for one to last more than 40 years with only a minimal amount of care. But, occasionally, water will begin to leak out from under the toilet and spill onto the floor, which can lead to serious water damage. But this type of leak is easy to diagnose and fix, even if you’ve never attempted a plumbing repair.

Why is the toilet is leaking from the base?

The leak is usually caused when the seal under the toilet fails. Below you’ll learn how to install a new wax gasket to create a watertight seal between the toilet and the closet flange and install a new flexible water-supply tube.

Water pooling around the base of the toilet is a good indication that the wax seal has failed. But in some cases the problem lies elsewhere. Soak up the water from the floor with a sponge and dry off the toilet with a towel. Wait until a new puddle appears on the floor, then check to make sure the water is seeping out from under the toilet and not coming from a loose supply tube, faulty shutoff valve, cracked tank or sweaty bowl.

How do you fix it?

If water is leaking from beneath the toilet, you might be able to stop it by simply tightening the closet bolts that secure the toilet to the floor. Use a putty knife or slotted screwdriver to pry off the caps that are covering the bolts. Then use a wrench to alternately tighten each bolt, a little at a time. Be careful not to apply too much pressure; you can crack the toilet’s base.

If you’re lucky, the leak will stop. If tightening the bolts doesn’t help, you’ll have to remove the toilet and replace the wax gasket.

Removing The Toilet

The first step to replacing a wax gasket on a toilet is to turn off the water at the shutoff valve, which is usually located behind the toilet, or in the basem*nt or crawl space directly below it. Turn the handle all the way in a clockwise direction.

Remove the tank lid, flush the toilet and hold down the handle to drain as much water as possible from the tank. Use a sponge to get up the remaining water in the tank; a small paper cup will help you remove any water left in the bowl.

Next, disconnect the water-supply tube by loosening the compression nut on the shutoff valve (step 1). Pry the caps from the closet bolts, then use a wrench to remove the nuts (step 2). If either bolt spins as you turn the nut, hold the top of the bolt with needlenose pliers.

Grab the rim of the bowl directly below the seat hinges, and gently rock the toilet back and forth to break the wax seal. Lift the toilet off the floor (step 3) and lay it on a blanket or piece of cardboard. Use a narrow putty knife to scrape off the old wax gasket from the bottom of the toilet and from the closet flange in the floor (step 4).

Check the condition of the flange to make sure it isn’t cracked or bent. After we scraped off the wax, we discovered that a large piece of the flange had broken off. If this happens, you can replace the entire flange (no easy task), install a full replacement flange or fill in the missing piece with a repair strap. We opted for the easiest, least expensive option and used the Gapper Flange Repair Strap (about $5) from Jones Stephens Corporation.

To install the curved metal strap, first loosen the two screws that secure the flange to the floor. Insert a new closet bolt into the slot in the strap, then slide the strap under the flange (step 5). Tighten the flange screws to lock the strap in place. Install the remaining closet bolt in the flange. If the bolts won’t stand upright, pack a little wax from the old gasket around the base of each one.

Take a new wax gasket and set it down on the closet flange, making sure it’s perfectly centered (step 6). Most wax gaskets are simply a ring of solid wax, but we used Harvey’s Bol-Wax No. 5 (about $5). This one has wax surrounding a core of soft urethane foam, and it easily conforms to the flange and toilet to create a superior seal.

Replacing The Toilet

If the toilet is fitted with an old chrome-plated copper supply tube, consider replacing it with a new flexible one made of stainless steel-enmeshed polymer. It makes the installation a whole lot easier, and it will virtually last forever. We installed a 12-in.-long Fluidmaster supply tube (about $5); other lengths are available ranging from about 8 to 24 in.

Apply a light coating of pipe-joint compound to the fitting at each end of the supply tube, then tighten one end onto the fill-valve shank protruding from the bottom of the toilet tank (step 7).

You’re now ready to set the toilet back in place. Grip the bowl near the seat hinges, lift up the toilet and walk it over to the flange. Set the toilet down onto the wax gasket, using the closet bolts as guides. Slip the washers over the bolts and thread on the nuts. However, before tightening them, press down on the rim of the bowl with all your weight to compress the gasket (step 8).

Check to make sure the toilet tank is parallel with the back wall. Alternately tighten each closet bolt until both feel snug. Then, press down on the bowl again and tighten the nuts a little more. Continue in this manner until the nuts no longer feel loose after you press down on the toilet. Again, be careful not to exert too much pressure with the wrench or you’ll crack the toilet. Use a hacksaw to cut the closet bolts nearly flush with the nuts (step 9), then snap on the bolt caps.

Your final step is to tighten the loose end of the water-supply tube to the shutoff valve (step 10). Open up the valve and flush the toilet several times. If a leak occurs, press down on the bowl and tighten the nuts a little more. If it isn’t leaking, use the toilet for a couple of weeks, then pry off the bolt caps and retighten the nuts. The toilet will often settle after several uses.

The Caulk Question

There’s a long-standing debate in the plumbing world over whether you should caulk around the base of a toilet. Most plumbers don’t because they’re concerned that the caulk would conceal any leaks. However, in some municipalities, the local building code requires homeowners to caulk around the toilet to keep bacteria from growing in the joint.

Check with your building department for the code requirement in your town. If you do decide to caulk, be sure to use a high-quality, mildewproof tub-and-tile caulk.

Step by Step Instructions

1. Disconnect the supply tube from the shutoff valve using a wrench. Be sure the valve is closed and the toilet is drained.
2. Pry off the rounded caps that cover the closet bolts, then use a wrench to remove the hex nuts.
3. Very carefully lift the toilet by the bowl, not the tank, and set it down on an old blanket or cardboard sheet.
4. Scrape off all of the old wax gasket from the closet flange. Note that a section of the flange is broken off.
5. Slide a repair strap under the closet flange after loosening the screws that secure the flange to the floor.
6. Set the new wax gasket down on the closet flange, making sure it’s centered. Note: Both closet bolts are in place.
7. Connect the new water-supply tube to the threaded fill-valve shank on the bottom of the toilet tank.
8. Press down on the toilet bowl rim to compress the gasket. Tighten the closet bolts, then press down again.
9. Use a close-quarter hacksaw to trim off the tops of the closet bolts. Tighten the nuts before replacing the caps.
10. Connect the supply tube to the shutoff valve. Then open the valve, flush the toilet and check for leaks.

Where to find it:

Fluidmaster

30800 Rancho Viejo Rd.
Dept. TH400
San Juan Capistrano, CA 92675
www.fluidmaster.com
800/631-2011

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